Enthalpic Effects in Competitive Polymer Adsorption: Adsorption Isotope Effect and Chain End Effect

Peter Frantz, Dagmar C. Leonhardt, Steve Granick

Research output: Contribution to journalArticle

Abstract

Competitive adsorption was studied of deuteriopolystyrene (PS), protio PS, and carboxylic acid terminated PS, from cyclohexane solutions (0.05 or 0.1 mg mL-1) onto a single surface of silicon oxide at 30.0°C. Surface excess mass of the polymer was measured by infrared spectroscopy in the mode of attenuated total reflection. In competitive adsorption using a family of polymer fractions, preferential adsorption was observed of the deuterio (versus protio) isotopes and of the carboxylic acid terminated (versus hydrogen-terminated) chains. From considerations of relative enthalpic and entropic tendencies toward adsorption, it was concluded that (a) the magnitude of the differential sticking enthalpy (deuterio versus protio isotope) was ≈80 J mol-1 (0.03 kT) per polystyrene repeat unit and (b) the magnitude of the differential sticking enthalpy (carboxylic acid terminated versus hydrogen-terminated chain) was ≈1.6 × 104 J mol-1 (6.4 kT) per carboxylic acid end group. The implications of these findings for competitive adsorption when samples contain traces of polar impurities (for example, of oxidation impurities) are discussed quantitatively.

Original languageEnglish (US)
Pages (from-to)1868-1875
Number of pages8
JournalMacromolecules
Volume24
Issue number8
DOIs
StatePublished - Apr 1 1991

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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